JP5491894B2 - Semiconductor relay - Google Patents

Description

  The present invention relates to a semiconductor relay.

  Conventionally, a semiconductor relay called a MOSFET output photocoupler or an optical MOSFET has been provided (see, for example, Patent Document 1).

  An example of the semiconductor relay 1 is shown in FIGS. This semiconductor relay 1 has two input terminal portions 51 and two output terminal portions 61. Further, the semiconductor relay 1 includes a light emitting element 2 connected between the input terminal portions 51, two MOSFETs 3 a and 3 b connected in series between the output terminal portions 61, and the presence or absence of light from the light emitting element 2. The light receiving drive element 4 for driving the MOSFETs 3a and 3b on and off according to the above is provided.

  The light emitting element 2 has a pair of terminals that are electrically connected to the respective input terminal portions 51, and emits light when predetermined power (for example, DC power of a predetermined voltage) is input between the terminals. To do. For example, a light emitting diode can be used as the light emitting element 2.

  The light receiving drive element 4 receives light from the light emitting element 2 to generate power, for example, a light receiving element 4a composed of a photodiode array (so-called solar cell), and a period during which the light receiving element 4a generates power. Each MOSFET 3a, 3b is driven on, and a driving circuit 4b that drives each MOSFET 3a, 3b off during a period when the light receiving element 4a does not generate power is integrated on one chip. Since the light receiving drive element 4 as described above can be realized by a well-known technique, a detailed description thereof is omitted.

  Each of the MOSFETs 3a and 3b is an N-channel type, and the source electrodes 31 are electrically connected to each other, and the gate electrode 32 and the source electrode 31 are electrically connected to the drive circuit 4b of the light receiving drive element 4, respectively. The drain electrode 33 is electrically connected to one of the output terminal portions 61. That is, since the parasitic diodes of the MOSFETs 3a and 3b are opposite to each other, the electrical connection (conduction) between the output terminal portions 61 connected to one end of the series circuit of the two MOSFETs 3a and 3b is turned on / off. Regardless of the direction of the voltage input between the output terminal portions 61, it depends on the on / off states of the MOSFETs 3a and 3b.

  The operation of the semiconductor relay 1 will be described. During a period in which the predetermined power is not inputted between the input terminal portions 51 and the light emitting element 2 is turned off, the MOSFETs 3a and 3b are maintained in the off state, and thus the electrical connection between the output terminal portions 61 is turned off. The

  When the light emitting element 2 is turned on by inputting predetermined power between the input terminal portions 51, the light receiving drive element 4 drives each of the MOSFETs 3a and 3b to turn on the electrical connection between the output terminal portions 61. Is done.

  When the light emitting element 2 is turned off, the light receiving drive element 4 drives the MOSFETs 3a and 3b to turn off, whereby the electrical connection between the output terminal portions 61 is turned off again.

  Here, the semiconductor relay 1 includes a sealing resin 10 that seals the light emitting element 2, the MOSFETs 3 a and 3 b, and the light receiving drive element 4. A synthetic resin that transmits light from the light emitting element 2 is used at least between the light emitting element 2 and the light receiving element 4 a of the light receiving drive element 4 in the sealing resin 10.

  Further, the semiconductor relay 1 is composed of two input conductive plates 5 each having a connection portion 52 made of a conductive material and electrically connected to one terminal of the light emitting element 2 in the sealing resin 10. Is provided. The connection portion 52 of one input conductive plate 5 is one in which one terminal of the light emitting element 2 is surface-mounted (surface mounted), and the connection portion 52 of the other input conductive plate 5 is connected to the other terminal of the light emitting element 2. It is electrically connected by wire bonding. Each input conductive plate 5 has an input terminal portion 51 that protrudes outside the sealing resin 10. Each input conductive plate 5 can be formed by punching and bending a metal plate, for example.

  Further, the semiconductor relay 1 includes two output conductive plates 6 each having a mounting portion 62 that is made of a conductive material and surface-mounted with one of the drain electrodes 33 of the MOSFETs 3 a and 3 b in the sealing resin 10. A central conductive plate 7 made of a material and having a flat shape, the light receiving drive element 4 being surface-mounted and sealed with a sealing resin 10 is provided. Each output conductive plate 6 and the central conductive plate 7 can be formed by punching and bending a metal plate, like the input conductive plate 5. In each of the MOSFETs 3a and 3b, the source electrodes 31 are electrically connected to each other by wire bonding, and the gate electrode 32 is electrically connected to the light receiving drive element 4 by wire bonding. Further, the source electrode 31 of one MOSFET 3a and the light receiving drive element 4 are electrically connected to the central conductive plate 7 by wire bonding, respectively, so that the source electrodes 31 of the MOSFETs 3a and 3b are respectively connected via the central conductive plate 7. The light receiving drive element 4 is electrically connected. Each output conductive plate 6 has an output terminal portion 61 that protrudes outside the sealing resin 10.

  As shown in FIGS. 11 and 12, each input terminal portion 51 and each output terminal portion 61 are formed on conductive patterns P1 and P2 provided on the mounting surface (upper surface in FIG. 12) of the common printed wiring board P, respectively. On the other hand, it is surface-mounted.

  Conventionally, the thickness direction of each mounting portion 62 and the central conductive plate 7 is matched with the thickness direction of the printed wiring board P.

JP 2003-8050 A

  By the way, when a high frequency signal is transmitted between the output terminal portions 61, the central conductive plate 7 connected to the source electrode 31 of each of the MOSFETs 3a and 3b functions as a so-called stub circuit. A signal flows in.

  Furthermore, in the printed wiring board P, for example, for the purpose of shielding electromagnetic noise, a conductive pattern P3 having the same potential as the ground may be provided over the entire non-mounting surface (the lower surface in FIG. 12). In this case, a parasitic capacitance Cp is generated between the mounting portion 62 and the central conductive plate 7 of each output conductive plate 6 facing each other and the ground pattern P3. Then, a high frequency signal flows out from the mounting portion 62 of each output conductive plate 6 and the central conductive plate 7 through the parasitic capacitance Cp, and thus the insertion loss is increased.

  This invention is made | formed in view of the said reason, The objective is to provide the semiconductor relay which can reduce an insertion loss.

In the first invention, two MOSFETs connected in series so that the directions of the parasitic diodes are opposite to each other, and a pair of terminals, and light emission that emits light when predetermined power is input between the terminals An element, a light receiving drive element that drives the two MOSFETs on and off according to whether or not the light emitting element emits light, and one end of a series circuit of the two MOSFETs, each made of a conductive material, are electrically connected. Two output conductive plates, two input conductive plates each made of a conductive material and electrically connected to one terminal of the light emitting element, the two MOSFETs, the light emitting element, and the light receiving drive A sealing resin that seals the element, the two output conductive plates, and the two input conductive plates, respectively, the two output conductive plates and the two input conductive plates, Said seal A terminal portion that protrudes outward from the resin and is mounted on a common printed wiring board, and each of the two output conductive plates is a mounting portion on which one of the two MOSFETs is mounted. Each mounting part is sealed with the sealing resin in such a direction that the thickness direction intersects the thickness direction of the printed wiring board, and the two MOSFETs are The light receiving drive element and the printed wiring board are sealed at a position sandwiched between them.

  A second invention is characterized in that, in the first invention, the two MOSFETs are integrated on one chip.

  A third invention is characterized in that, in the first invention, each of the two MOSFETs is surface-mounted on one of the output conductive plates.

  According to a fourth invention, in the first invention, a connection point between the two MOSFETs is electrically connected to the light receiving drive element by direct wire bonding.

  According to a fifth invention, in the first invention, the light receiving drive element is fixed and the thickness direction intersects the thickness direction of the printed wiring board in a flat shape made of a conductive material. A central conductive plate sealed with the sealing resin is provided, and a connection point between the two MOSFETs and the light receiving drive element are electrically connected to the central conductive plate by wire bonding, respectively. It is characterized by.

  According to the present invention, each mounting portion is sealed with the sealing resin in such a direction that the thickness direction intersects the thickness direction of the printed wiring board on which each terminal portion is mounted. Therefore, compared with the case where each mounting part is parallel to the thickness direction of the printed wiring board, it may occur between the conductive pattern of the printed wiring board and each mounting part. By reducing the parasitic capacitance, the insertion loss can be reduced.

It is a front view which shows embodiment of this invention. (A) and (b) are perspective views showing the same as seen from different viewpoints. It is a left view which shows the principal part same as the above. It is explanatory drawing which shows a frequency characteristic about each of a same as the above (curve B) and a prior art example (curve A). It is a perspective view which shows the example of a change same as the above. It is a left view which shows the principal part of the example of FIG. It is a perspective view which shows another example of a change same as the above. It is a left view which shows the principal part of the example of FIG. It is a circuit block diagram which shows a semiconductor relay. It is a perspective view which shows a prior art example. It is a partially broken plan view showing the same. It is a front view showing the same.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  Since the basic configuration of this embodiment is the same as that of the conventional example described with reference to FIGS. 9 to 12, the description of the common parts is omitted.

  In the present embodiment, as shown in FIG. 1, the central conductive plate 7 and each mounting portion 62 are each in the thickness direction with respect to the thickness direction of the printed wiring board P on which the terminal portions 51 and 61 are surface-mounted. The directions are orthogonal to each other.

  Specifically, each of the input conductive plates 5 and each of the output conductive plates 6 is formed in an L shape that is bent substantially at a right angle once in the thickness direction, and one side of the bent portion. The input terminal part 51 or the output terminal part 61 which is a terminal part is formed respectively, and the connection part 52 or the mounting part 62 is formed on the other side.

  Further, the electrical connection of the source electrode 31 of the MOSFET 3a to the light receiving drive element 4 is achieved not by the central conductive plate 7 as in the conventional example but by direct wire bonding as shown in FIG. As a result, the number of wire bondings required is reduced compared to the case where the source electrode 31 of the MOSFET 3a is connected to the light receiving drive element 4 via the central conductive plate 7 as in the conventional example.

  Further, the drain electrodes 33 (see FIG. 9) of each MOSFET 3 a and 3 b are surface-mounted on the mounting portion 62 of the output conductive plate 6. As a result, the current capacity can be increased as compared with the case where the electrical connection between the drain electrode 33 and the mounting portion 62 of each MOSFET 3a, 3b is achieved by wire bonding. The capacity could be doubled or more.

  Further, the sealing resin 10 has a rectangular parallelepiped shape as a whole, and the semiconductor relay 1 is surface-mounted on the printed wiring board P with one surface (the lower surface in FIG. 1) facing the printed wiring board P. .

  Hereinafter, the top, bottom, left, and right are based on FIG. 1, and the front direction (the lower left direction in FIG. 2A) of the directions orthogonal to the paper surface of FIG. Note that the above direction is defined for convenience of explanation, and does not necessarily match the direction in the actual use state.

  The central conductive plate 7 has a flat shape with the thickness direction directed in the left-right direction, and has arm portions 71 projecting from the upper end to both the front and rear sides. At the time of manufacturing, when sealing with the sealing resin 10, the central conductive plate 7 and the light receiving drive element 4 are each supported by the arm portion 71.

  In addition, each input terminal portion 51 and each output terminal portion 61 are substantially flush with the lower surface of the sealing resin 10 on the surface of the both sides in the thickness direction where the connection portion 52 and the mounting portion 62 do not protrude. . Furthermore, the input terminal portions 51 are arranged side by side at the lower end portion of the left surface of the sealing resin 10 and protrude leftward, and the output terminal portions 61 are arranged at the lower end portion of the right surface of the sealing resin 10 and are aligned to the right. It protrudes toward.

  Further, the central conductive plate 7 and each mounting portion 62 are sealed in a direction in which both front and back surfaces are parallel to the left and right surfaces that are orthogonal to the one surface of the surface of the sealing resin 10. . That is, the thickness direction of the central conductive plate 7 and each mounting portion 62 is set to be orthogonal to the thickness direction of the printed wiring board P.

  According to the said structure, compared with the case where each mounting part 62 makes the thickness direction parallel with respect to the thickness direction of the printed wiring board P in which each terminal part 51 and 61 is each mounted, said printed wiring board Insertion loss is suppressed by reducing the parasitic capacitance that may occur between the P conductive pattern P3 and each mounting portion 62. In FIG. 4, the analysis result of the insertion loss in the conventional example described in FIGS. 10 to 12 is shown by a curve A, and the analysis result of the insertion loss in this embodiment is shown by a curve B. As can be seen from FIG. 4, in this embodiment, the insertion loss is suppressed as compared with the conventional example.

  As shown in FIGS. 5 and 6, the source electrode 31 of the MOSFET 3a may be electrically connected to the light receiving drive element 4 through the central conductive plate 7 as in the conventional example. That is, the source electrode 31 of the MOSFET 3a (that is, the connection point between the two MOSFETs 3a and 3b) and the light receiving drive element 4 are electrically connected to the central conductive plate 7 by wire bonding. In this case, since the source electrode 31 of each of the MOSFETs 3 a and 3 b is also mounted on the central conductive plate 7 by wire bonding, a high frequency signal transmitted between the output terminal portions 61 flows into the central conductive plate 7. However, since the thickness direction of the central conductive plate 7 is also orthogonal to the thickness direction of the printed wiring board P, an increase in insertion loss can be suppressed regardless of the inflow of the high-frequency signal as described above. When the above configuration is adopted, the number of times of wire bonding required at the time of manufacture increases as compared with the examples of FIGS. 1 to 3, but the rate of decrease in the gate-source voltage of each MOSFET 3a, 3b can be increased. The turn-off time of the semiconductor relay 1 can be shortened. According to the experiment by the present inventor, the turn-off time in the example of FIGS. 5 and 6 can be reduced to half or less as compared with the example of FIGS.

  Further, as shown in FIGS. 7 and 8, a switching element 3 in which two MOSFETs 3a and 3b are integrated on one chip may be used. Since such a switching element 3 can be realized by a well-known technique, detailed illustration and description thereof are omitted. In the example of FIGS. 7 and 8, the switching element 3 is fixed to the surface on the same side as the light receiving drive element 4 in the central conductive plate 7. Each of the MOSFETs 3a and 3b included in the switching element 3 has a source electrode 31 (that is, a connection point between the two MOSFETs 3a and 3b) mounted on the central conductive plate 7 by wire bonding. 32 is electrically connected to the light receiving drive element 4 by direct wire bonding, and the drain electrode 33 is mounted to the mounting portion 62 of each output conductive plate 6 by wire bonding. If appropriate integration is performed as described above, the number of parts can be reduced.

  Furthermore, instead of adopting a configuration in which each terminal portion 51, 61 is surface-mounted on one surface in the thickness direction, each terminal portion 51, 61 is surface-mounted on the lower end surface with the thickness direction facing in the left-right direction. It is good also as a structure. In this case, each of the input conductive plates 5 and each of the output conductive plates 6 can have a flat shape that does not have a bent portion.

DESCRIPTION OF SYMBOLS 1 Semiconductor relay 2 Light emitting element 3a, 3b MOSFET
4 Light receiving drive element 5 Input conductive plate 6 Output conductive plate 7 Center conductive plate 31 Source electrode (connection point of two MOSFETs)
51 Input terminal portion 61 Output terminal portion 62 Mounting portion P Printed wiring board

Claims (5)

Two MOSFETs connected in series so that the directions of the parasitic diodes are opposite to each other;
A light emitting element that has a pair of terminals and emits light when a predetermined power is input between the terminals;
A light receiving drive element for turning on and off the two MOSFETs according to whether the light emitting element emits light;
Two output conductive plates each made of a conductive material and electrically connected to one end of the series circuit of the two MOSFETs;
Two input conductive plates each made of a conductive material and electrically connected to one terminal of the light emitting element;
A sealing resin for sealing the two MOSFETs, the light emitting element, the light receiving drive element, the two output conductive plates, and the two input conductive plates;
The two output conductive plates and the two input conductive plates each have a terminal portion that protrudes outside the sealing resin and is mounted on a common printed wiring board.
Each of the two output conductive plates has a mounting portion on which one of the two MOSFETs is mounted,
Each of the mounting parts is sealed in the sealing resin in such a direction that the thickness direction intersects the thickness direction of the printed wiring board ,
The two MOSFETs are sealed at a position sandwiched between the light receiving drive element and the printed wiring board .   2. The semiconductor relay according to claim 1, wherein the two MOSFETs are integrated on one chip.   The semiconductor relay according to claim 1, wherein each of the two MOSFETs is surface-mounted on one of the output conductive plates.   2. The semiconductor relay according to claim 1, wherein a connection point between the two MOSFETs is electrically connected to the light receiving drive element by direct wire bonding. A central conductive plate made of a conductive material and having a flat shape and sealed with the sealing resin in such a direction that the light receiving drive element is fixed and the thickness direction intersects the thickness direction of the printed wiring board With
2. The semiconductor relay according to claim 1, wherein a connection point between the two MOSFETs and the light receiving drive element are electrically connected to a central conductive plate by wire bonding, respectively.

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